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From "Stu Hood (JIRA)" <j...@apache.org>
Subject [jira] Issue Comment Edited: (CASSANDRA-1046) optimize Memtable.getSliceIterator
Date Thu, 13 May 2010 23:55:43 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-1046?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12864526#action_12864526
] 

Stu Hood edited comment on CASSANDRA-1046 at 5/13/10 7:54 PM:
--------------------------------------------------------------

That's only one of the bullet points on #998: please wait to see the code before vetoing it
entirely.

EDIT: Having posted the first patch for #998, I agree that it no parts of it should touch
0.7. But, we should still consider the fact that 998 will be coming with 0.8, and weigh the
benefits of fixing this issue against fixing other issues that don't touch queries/column
iteration.

      was (Author: stuhood):
    That's only one of the bullet points on #998: please wait to see the code before vetoing
it entirely.
  
> optimize Memtable.getSliceIterator
> ----------------------------------
>
>                 Key: CASSANDRA-1046
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-1046
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Jonathan Ellis
>             Fix For: 0.7
>
>
> As reported by James Golick, about 30% of the time in a read is spent in SliceQueryFilter.getMemColumnIterator,
virtually all of which is in ConcurrentSkipListMap$Values.toArrray().
> I wrote on the ML:
> Besides the UUID optimization you posted, we should do an audit of ColumnFamily.getSortedColumns
and replace with iteration where possible (in this case, we'd be left with one copy of most
of the columns, but that's better than two).
> We can get rid of the other copy by fixing the logic in Memtable.getSliceIterator, which
says "copy all the columns, so we can do a binary search on them to find where to start,"
but since columns are natively in sorted order we could just use an iterator and a while loo

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